OBJECTIVES: 1. To characterize axonal transport of protein in mammalian optic axons before and after the onset of functional visual activity in terms of a) optic nerve synaptosomal plasma proteins and their biological half-life in the nerve ending; b) transport rate and biological half-life of (Na ion plus K ion)-dependent ATPase in the optic nerve; c) the composition of early and late phases of slow transport in the optic nerve. 2. To examine the physiological significance of transneuronal transfer of radioactivity within the mammalian visual system by determining its plasticity in terms of a) developmental changes before and after eye-opening; b) response to visual system lesions in the neonate and adult. 3. To determine the plasticity of retograde axonal transport in the mammalian optic nerve before and after eye-opening and in response to visual system lesions in the neonate and adult.